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In order for the diesel to reach a supercritical state, Anitescu's fuel system has first to heat it to around 450 degrees Celsius at a pressure of about 60,000,000 Pascal. Achieving the pressure is not a problem, Anitescu says, but increasing the temperature is more demanding.
Because fuel systems usually operate at temperatures below 80 degree Celsius, Anitescu and his colleagues used the heat from the engine's exhaust to raise the fuel's temperature. This causes further complications. "You need to prevent it from coking," he says. Coking occurs when hydrocarbons in the fuel react, producing sticky deposits that can lead to fuel-system failures. The phenomenon can be avoided by diluting the fuel with an additive, such as carbon dioxide or water. In the Syracuse engine, a small amount of exhaust gas is introduced to act as an anticoking agent, a technique known as exhaust-gas recirculation.
The system has only been tested in a laboratory setup, but a prototype could be ready for testing by the end of the year, says Anitescu. The fuel system is designed to use conventional fuel injectors, even though these are designed to work with regular fluids. Anitescu says it may be possible to improve the performance by switching to a fluid state just below supercritical. This may allow vaporization to occur while getting better performance out of the injectors. "We have many options here," he says.
At the same conference, Transonic Combustion, a company based in of Camarillo, CA, presented details of an alternative way to use supercritical fuels that involves a novel fuel injector and redesigning the engine's entire valve system and combustion chamber.
But with either approach, going supercritical does not come without a cost, says Birgel. "You still need the viscosity because most diesel fuel systems depend upon the fuel for lubrication," he says.
"This is an issue which has yet to be addressed," admits Anitescu. He says it may be possible to introduce lubricants, but this would only be necessary in the final stage of the fuel system, where the fluid is at its hottest. For subcritical fuels, it may not be an issue, he says.
Satellite navigation technology is focusing on reducing fuel consumption.
Amyris's large-scale demonstration plant will make diesel from sugarcane.
Cool stuff, I am always for people who use pre-existing components in new designs, in this case using existing fuel injectors. This makes the adoption of new system much easier. Even if they get the system to increase fuel efficiency by 5 to 10 mph, that is a great improvement and would render the system commercially attractive.
Dr. Brian Glassman
Ph.D in Innovation Management from Purdue University
Point of use inputs, whether as above commented, or even as supplemental hydrogen, have those advantages. Actually certain fairly cheap additives can be used, even co-injected, with particular good effect in higher-compression engines such as Diesel. Excellent test results have been achieved in efficiency and emissions using non-exotic additive blends, intended for mass distribution, depots, but not consumer individual action. The actual problems seem more to be in gaining 'establishment' acceptance, particularly where it is invested in the status quo and current 'solutions'. Air quality is much better, but less platinum might be needed, etc.
N.Evans
Manufacturing in the United States is in trouble. That's bad news not just for the country's economy but for the future of innovation.
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kitk
76 Comments
Fuel vaporization
Call it super critical fuel, it is still fuel vaporization, give or take a technial detail. This has been around a long time, and held loads of promise, but was always dangerous or too difficult.
Yet, I have seen cars on boiled gas get mileage two or three times anything normally seen on the road today. Yeah, it works.
I really, REALLY hope this can be made to work. But, there are simpler, and safer ways to do it besides pumping in heat. Some humidifiers vaporize water through sound waves. And microwaves, or some other spectrum, might be able to flash the fuel as it exits nozzels into the cylander. This could allow the rest of the fuel to be normal liquid, and only a minute amount super critical at a given time. Further, if the engine stops for any reason, so would the vaporization, safely.
It only require a measured radiation in just the right place, to do the job.
Someone, please pass it on!
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rrcoscia
1 Comment
Re: Fuel vaporization
Yes, I read about an ultrasonic nebulizing carburator several years ago. An ultrasonic nebulizer can produce droblets at about 1.5 microns. (I think the nebulizer can be tuned to optimize the sizes.) Supposedly, the nebulizing carburator could get 30 miles/gallon from cars that were getting 10-12 mpg. I'm not sure how the technology would work with an injector, but the carburator basically put a nebulizing surface in the throat of the carburetor and when gasoline hit it it would instantly become extremely small droplets.
Of interest in this article is that the high pressure apparently breaks the bonds of the hydrocarbons and changes the chemical structure. (The nebulizer isn't able to do that.) The benefit generally is that the smaller the hydrocarbon, the better the burn (methane CH4, the simplest hydrocarbon, burns completely to CO2 & water.) So the nebulizer and pressure work differently but both are very intriguing.
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